Reading Green Speed: The Stimpmeter Explained

A Stimpmeter reading is the distance, in feet, that a golf ball rolls after leaving a notched metal bar held at a fixed angle, averaged over several rolls on a flat section of green. It is the standard way a superintendent describes how fast a putting surface is running, and it is also only a measurement of that one flat strip on that one morning, not a description of how every putt on the green will behave. A crew that reads the number without reading the green behind it will chase a speed target and still get complaints about greens that putt fast in one spot and slow in another.

How is a Stimpmeter reading actually taken

The Stimpmeter is a grooved bar, roughly three feet long, with a notch near one end set at a fixed release angle. A ball is placed in the notch and the bar is slowly raised until the ball rolls off under its own weight, which gives every roll the same starting speed regardless of who is holding the bar. The test is run on a flat, representative section of the green, away from slopes and collars, and the ball is rolled in one direction, then the bar is moved to the stopping point and the ball is rolled back the opposite way. Three rolls each direction is the usual count, and the readings in each direction should be close to each other; a wide gap between the two directions usually means the test section was not as flat as it looked, not that the green rolls differently depending on direction. The distances from both directions are averaged into a single number, reported in feet, such as a green that stimps at nine feet.

What does a green speed number actually mean for play

The number describes friction and firmness on that strip, not slope or contour. A nine-foot green and an eleven-foot green both describe how far a ball rolls from the same release speed; the higher number means less resistance, from a lower cut, firmer footing, drier surface, or a finer-bladed turf holding up well under that cut. Daily-play courses commonly run greens in the high single digits to around nine feet, because members are putting on greens with real slope and a number much higher than that turns ordinary contours unplayable. Tournament setups, where the committee controls pin placement and slope tolerance carefully for the week, often push into the low teens, and famously fast greens at major championship venues have been described in the low-to-mid teens, which is only playable because the pin positions and the contours are chosen to match that speed, not because the grass itself is cut any differently than careful daily maintenance could achieve.

Why can two greens read the same speed and still play differently

The Stimpmeter measures one flat strip, and most greens are not flat. A green that stimps at nine on its flattest pad can still have a false front, a back shelf, or a ridge where the same ball breaks hard and rolls well past where the flat-strip number would suggest. The USGA Green Section has long cautioned superintendents against treating a single Stimpmeter reading as a target to chase across an entire green complex, since a crew that mows every green to hit one number can end up with greens that are unputtable on their steeper sections even though the measured speed looks consistent on paper.

Moisture and firmness change the picture further. A green rolled dry in the afternoon reads faster than the same green measured on dewy morning turf, and a green that has just been topdressed or aerated reads slower than it will a week later once the surface heals. A reading taken once a week tells the crew a trend, not the speed golfers are experiencing on any single afternoon.

How does the height of cut relate to the Stimpmeter reading

Height of cut is the lever a crew pulls most often to move the number, but it is not the only one. Lowering the cut by a few thousandths of an inch raises speed, but it also stresses the plant, and a green pushed too low for its grass species and the season will thin out before it speeds up any further. Rolling, firming the surface with water management, and brushing the canopy upright before mowing all move the reading without cutting any lower, and a crew managing a stressed green in midsummer often reaches for those tools instead of the mower.

What a superintendent does with the daily reading

Most courses that Stimp regularly do it on two or three representative greens rather than all eighteen every day, logging the number alongside the height of cut, the weather, and any recent cultural work such as topdressing or verticutting. That log is what lets a crew tell the difference between a green that is genuinely getting faster and a green that only reads faster because the test strip happened to be drier that morning. A number without that context is a single data point; a number read against the log, the contour map, and the day's weather is a management tool. The reading tells a crew where the surface sits today. Reading the green itself, the slope, the grain, the moisture, still decides what the crew does about it.